Cleansing compositions for use on or near skin and/or eyes have to fulfill many different requirements. Typically, good cleansing properties and high foam volume require higher levels of detergents, which tend to be irritating to skin and/or eyes. Hence, it is desirable to reduce the concentration of detergent used in a composition, while maintaining good cleansing and foaming properties. For certain compositions it is desirable to combine the ability to suspend insoluble components, such as scrubbing beads or gas bubbles, while having good clarity of the liquid phase of the composition, such that the suspended components can be easily seen throughout the composition. For certain compositions it is desirable to have an acidic pH instead of a neutral or more basic pH to e.g. allow utilization of organic acid derivatives as preservatives or benefit agents, such as benzoic acid as an effective preservative or salicylic acid as an anti-acne agent.
While there are certain attempts to address the above requirements individually, it is desirable to generate cleansing compositions exhibiting a yield stress value sufficient to suspend insoluble components, and having a good clarity, and having a pH below neutral (acidic), and maintaining mildness to skin and/or eyes while having good cleansing and foaming properties. Typically, rheology modifiers providing a yield stress value to a composition render the composition turbid, especially in presence of only a medium or low concentration of surfactant. Some rheology modifier polymers providing a yield stress value can generate clear compositions at a pH above 6.5, but will render the composition turbid at acidic pH, again in presence of a medium to low concentration of surfactant. Acrylates Copolymer like Carbopol® Aqua SF-1 is an example of the latter. Certain attempts to produce clear suspending compositions at a pH below 6.5 using polymers like Acrylates Copolymer as a suspending polymer have included utilization of high amounts of anionic surfactant in the composition. A high concentration of surfactant can improve clarity, but render the composition irritating to skin and eyes and thus, is undesirable. Certain attempts to produce clear suspending compositions at a pH below 6.5 have included the use of acid swellable suspending polymers, e.g. a Polyacrylate-1 Crosspolymer like Carbopol® Aqua CC. However, also these polymers require high amounts of anionic surfactant to generate clear compositions and thus, are undesirable. The polysaccharide derived rheology polymer xanthan gum can generate suspending compositions at a pH below 6.5, but this polymer becomes less efficient at a pH below 6.5 compared with neutral and basic pH and more importantly, it is generating an undesirable texture and thus makes the composition undesirable for Personal Care use.
Certain attempts to produce milder cleansing compositions have included combining relatively low amounts of anionic surfactants, with relatively lower irritating surfactants such as nonionic and/or amphoteric surfactants, see, e.g. U.S. Pat. No. 4,726,915, or associating the anionic surfactants with amphoteric or cationic compounds in order to yield surfactant complexes, see, e.g., U.S. Pat. Nos. 4,443,362; 4,726,915; 4,186,113; and 4,110,263. Disadvantageously, mild cleansing compositions produced via both of such methods tend to suffer from relatively poor foaming and cleansing performance, and will not generate clear compositions when combined with suspending polymers such as Acrylates Copolymer (e.g. Carbopol® Aqua SF-1) or Polyacrylate-1 Crosspolymer (e.g. Carbopol® Aqua CC) at a pH below 6.5. Still another approach to producing mild cleansing compositions is to use polymerized surfactants having a relatively low degree-of-polymerization and at least about 10 mol % amphiphilic repeat units; see e.g. U.S. Pat. No. 7,417,020. Still another approach to producing mild cleansing compositions is to use super hydrophilic amphiphilic copolymers; see e.g. U.S. Pat. No. 8,258,250 B2. While they teach how to generate mild cleansing compositions, both the latter and the former approach do not teach how to generate mild and clear and suspending compositions at a pH of below 6.5.
Thus, while improvements have been made in providing solutions for the individual requirements or the combination of some of the requirements of cleansing compositions, the inventors have recognized that it is desirable to generate compositions fulfilling several requirements simultaneously: mildness to the skin and eyes, while maintaining good cleansing and foaming properties, the ability to suspend insoluble components, while having good clarity of the liquid phase of the composition, and having an acidic pH instead of a neutral or more basic pH to e.g., allow utilization of organic acid derivatives.